Meet Michigan’s 8 invasive insects: What they are, the damage they cause and what to do about them (2024)

Michigan has eight insects on its invasive species list.

If you see these insects, you should report them to the state and capture and kill them.

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Many of these insects threaten trees and plants across the state, some can have devastating effects if left unchecked.

  • More ‘Talk About Michigan’ coverage

  • If you believe you have found one of these invasive insects, you can report it through the Midwest Invasive Species Information Network. Just click here and search for the insect.

Spotted Lanternfly

If you see one, catch it and kill it.

Each spotted lanternfly can lay an egg mass containing around 30-50 eggs. If you see an egg mass, squish it.

These insects feed on more than 70 different plants including grapes, apples, hops and hardwood trees. It sucks sap from host plants while secreting large amounts of sugar-rich, sticky liquid called honeydew.

The honeydew and resulting black sooty mold can kill plants and foul surfaces. The honeydew attracts pests like yellow jackets, flies and ants.

There are some people online who are using water bottles or other plastic cups to capture the spotted lanternfly when they’re on trees. You simply put the mouth of the bottle around it and the lanternfly will fly into the bottle.

A small population of them was identified in Michigan earlier this month. If you find any spotted lanternfly, report them to MDARD via email at or by calling 800-292-3939. If you can, collect a specimen in a container for it to be verified.

Read: Invasive spotted lanternfly found in Michigan for first time: What to know

Japanese beetle

The Japanese beetle is widespread throughout Michigan.

Adult beetles are about 3/8 inch in length and have a bright, metallic green head and body and metallic brown wings. Its legs are a darker green. There are twelve tufts of white hairs surrounding the edges of the abdomen.

Grubs or larvae are about 1/16th to 1/4 inch in length, white and have three pairs of legs. Adult beetles emerge in June or July and feed throughout the summer.

The grubs live underground and feed on grass roots. They leave brown patches in lawns. The adults feed on foliage, flowers and fruit including tree fruits, small fruits, ornamentals, garden vegetables, soybeans and corn.

Read: 6 invasive insects to watch out for in Michigan

Spongy moth

Spongy moth caterpillars emerge from tan, fuzzy egg masses in April and feed on leaves through late June.

The caterpillars are hairy and have a yellow and black head, five pairs of blue spots followed by six pairs of red spots. Mature caterpillars are 1.5 to 2 inches in length.

If you find leaf debris and small, round frass under trees that’s an indication of a spongy moth infestation.

Male moths’ wings have a wavy pattern of brown to dark-brown and span 1.5 inches. Female moths are larger than males and do not fly. The females have white to cream color wings with wavy black markings.

The caterpillars are of concern because they can defoliate trees, leaving them vulnerable to diseases and other pests which can kill trees. Caterpillars can be blown by the wind to other trees.

Read: Invasive moth found in Michigan gets new name because of derogatory term

Emerald ash borer

The emerald ash borer is known to be established in Michigan’s lower peninsula.

They have a bright, metallic green body with purple abdominal segments under its wing covers. It’s about 1/2 inch long as an adult. It can fit on the head of a penny. The larvae are worm-like. They create a d-shaped exit hole in trees.

Adults feed on the foliage of ash trees while the larvae tunnel and feed on the underside of the park, which cuts off the transportation of nutrients and water to the tree.

They were first discovered in Michigan in 2002 and has killed tens of millions of ash trees in Michigan. It has killed trees in forests and neighborhoods.

Adults typically only fly 1/2 mile, but they can be transported through infested firewood to non-infested areas.

Read: 11 invasive species to watch out for in Michigan

Brown marmorated stink bug

The brown marmorated stink bug is established in Michigan.

It’s a 0.5-0.625-inch shield-shaped insect that uses its piercing mouthparts to suck plant juices from fruits, seed pods and nuts on many plants.

It was accidentally brought to North America from Asia in 1996. It was first detected in Michigan in 2010 and is now a major pest for farmers.

Stink bugs have been since been found in all Michigan counties but is well established in the southern part of the Lower Peninsula.

The good news is stink bugs will not cause structural damage or reproduce in homes. They also do not bite people or pets.

They are not known to transmit disease or cause physical harm but they have their name for a reason -- they produce a pungent chemical that -- well, it stinks.

Read more: Let’s talk about Michigan stink bugs: Why are they here? What should you do about it?

Asian Longhorned Beetle

It’s an invasive wood-boring beetle that attacks 12 types of hardwood trees, including maples, elms, horse chestnuts, birches and willows. It doesn’t have any predators or diseases to keep the population down.

When it’s in its larval stage, it feeds inside tree trunks and branches during the colder months. It creates tunnels as it feeds and then chews its way out as an adult in the warmer months.

Trees that have been invested will not survive.

Although the beetle has not yet been discovered in Michigan, officials say it’s “crucial we keep an eye out for it.” Discovering early signs of infestation can prevent widespread damage to the state’s forest resources, urban landscapes and maple syrup production.

Look for the following signs when you’re outside:

  • Round exit holes, about the diameter of a pencil, found in tree trunks and branches.

  • Shallow oval or round scars in the bark, where the adult beetle chewed an egg site.

  • Material that looks like wood shavings lying on the ground around the tree or in the branches.

  • Dead branches or limbs falling from an otherwise healthy-looking tree.

Adult Asian longhorned beetles are large and range from 3/4 to 1 1/2 inches in length. That doesn’t include their long antennae. They are shiny black and have random white blotches, or spots.

Read more: Start checking trees for signs of Asian longhorned beetles: What they are, why they’re a threat

Balsam woolly adelgid

Balsam woolly adelgid has been detected in Michigan.

It infests true fir trees, including balsam, fraser and concolor (white) fir in forests and landscapes in Michigan.

It’s a sap-feeding insect and its repeated attacks can weaken trees, cause twig gouting and causes trees to die over the course of several years.

Michigan officials say to watch out for the following signs:

  • Tiny one-to-two-millimeter white woolly tufts on the lower trunk of the tree and possibly on large branches in the spring and summer.

  • Swelling and distortion of the twigs, commonly called “gout”.

  • Flagging - a branch or branches that turn brick-red.

  • Tree crowns that become narrow and misshapen with few needles.

Read: Bug that could hurt Christmas tree industry found in West Michigan

Hemlock woolly adelgid

Hemlock woolly adelgid has been detected in Michigan.

It infests eastern hemlock trees and has been found in Michigan in forests and landscape settings. Eastern hemlock is found naturally in moist forest environments and along streams and water bodies.

The hemlock woolly adelgid sucks sap from the hemlock needles, killing needles, shoots and branches. Infested hemlocks become less vigorous and may turn grayish-green. If it’s untreated, it can kill a tree within four to 10 years.

Michigan says to watch out for the following signs:

  • Small, round, white, cottony masses, 1/16″ to 1/4″.

  • Found on the twig at the base of the needles on the underside of hemlock tree branches.

  • Present year-round but most visible November through July.

  • Note that hemlock woolly adelgid infests eastern hemlock trees, not pines or spruces.

Read: Time to check Christmas trees for hemlock woolly adelgid

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Meet Michigan’s 8 invasive insects: What they are, the damage they cause and what to do about them (2024)
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